Is it possible to add/change cultures?

[The Blind King of Bohemia]

There are three main cultures in the game - Catholic, Orthodox and Muslim. There is also Pagan. However, its kind of pointless. Is it possible to add things like battle orders for the Pagans? I wanted to import the Mongol ones from the Mongol Invasion and maybe try other things.

Also, can you create new ones? Since there are Jewish and Heretic relegions it would be cool if you could have cultures for them.

Finally, can you add religions or is it hardcoded? Thanks.

[NagatsukaShumi]

To my knowledge you can make Paganism a fully functioning religion with buildings, units and diplomatic peices and so on.

However I am not entirely sure about Jewish and Heretical religions, it maybe entirely possible however if you add all the folders that the other religions have to import these two into the game, adding religions is something I think is impossible to do.